The present invention relates generally to an escalator and, in particular, to lateral safety boundaries for continuous step escalators.
It long has been a goal of escalator manufacturers to counter the known latent danger of the catching of clothing or shoes between the traveling steps and the stationary skirt plates of escalators. National regulations prescribe a minimum safety precaution to keep the distance between the edge of a movable step and the adjoining skirt plate as small as possible, for example, the maximum distance at one side must not exceed 4 mm. This requirement is relatively difficult to maintain since certain inaccuracies cannot be excluded, due on the one hand to the plurality of movable steps which are aligned in an endless conveyor and due on the other hand to the skirt plates which are formed in lengths and fixed end-to-end adjacent to the path of travel of the conveyor. Both the step and the skirt plates are subject to manufacturing and installation tolerances.
An escalator is shown in the European patent document no. 0 297 233 in which each individual step has lateral safety boundaries which are supported in such a way that the outermost rib of the safety boundary, upon loading by a traveler, comes to rest on the skirt plate. The gap between the outermost rib of this step and the skirt plate is thereby locally closed, while this outermost rib slides along the skirt plate during the travel of the step conveyor. The disadvantage of this invention is that the gap between the individual steps and the skirt plate is only closed in those places where a traveler steps on the lateral edge of the tread plate or presses by some other forced action against the edge of the riser of a step.
Another similar safety device for escalators is shown in the U.S. Pat. No. 4,413,719 in which the lateral gap between the terminal ribs of the movable steps and the stationary skirt plates is completely closed by elastic synthetic material inserts. Since the gaps between the lateral edges of the traveling step conveyor and the stationary skirt plates vary, due to manufacturing and installation inaccuracies, a disadvantage of this device is that the sliding synthetic material inserts adjoining the skirt plates are pressed together more or less strongly which causes frictional losses and undesirable whistling or hissing noises.